This opened up whole new worlds for me and my PC gaming. The couch is a comfortable location now. Was using a beat up old 360 wired controller.
Battery Life: I put >80 hours into the witcher 3 before needing to replace the batteries. That's quite excellent.
Installation: Had a few issues pairing it because the device manager didn't give it the right drivers. If you have this issue you need to go into the device manager to human interface devices and change the microsoft input device to X360 controller. This is not word for word (just from memory) so if you have the issue just search on google with a few of those keywords and you'll find good instructions. Was fixed in 5 minutes. Other than that it was incredibly simple to install.
Range: Have the computer in one room. Long HDMI to my TV in another room. Has no problems connecting in the other room for me to play
Delay: I haven't noticed a large delay in commands to the games. It does exist, but it doesn't impact the gaming experience at all. same as on the 360 or XBONE.
This was about $10 more than the wired version and the freedom it adds is more than worth the $10 extra.